/scripts/binoffset.c
/***************************************************************************
* binoffset.c
* (C) 2002 Randy Dunlap <[email protected]>
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
# binoffset.c:
# - searches a (binary) file for a specified (binary) pattern
# - returns the offset of the located pattern or ~0 if not found
# - exits with exit status 0 normally or non-0 if pattern is not found
# or any other error occurs.
****************************************************************/
/*
*该程序用于在一个二进制文件中查找模式匹配的次数以及第一次匹配的位置
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#define VERSION "0.1" //程序版本号
#define BUF_SIZE (16 * 1024) //缓冲区大小
#define PAT_SIZE 100 //模式串的最大长度
char *progname;
char *inputname;
int inputfd;
unsigned int bix; /* buf index缓冲区索引 */
unsigned char patterns [PAT_SIZE] = {0}; /* byte-sized pattern array */
int pat_len; /* actual number of pattern bytes */
unsigned char *madr; /* mmap address */
size_t filesize;
int num_matches = 0;//匹配的次数
off_t firstloc = 0;//第一次匹配的位置
void usage (void)
{
fprintf (stderr, "%s ver. %s/n", progname, VERSION);
fprintf (stderr, "usage: %s filename pattern_bytes/n",
progname);
fprintf (stderr, " [prints location of pattern_bytes in file]/n");
exit (1);
}
//填充模式数组
void get_pattern (int pat_count, char *pats [])
{
int ix, err, tmp;
#ifdef DEBUG
fprintf (stderr,"get_pattern: count = %d/n", pat_count);
for (ix = 0; ix < pat_count; ix++)
fprintf (stderr, " pat # %d: [%s]/n", ix, pats[ix]);
#endif
for (ix = 0; ix < pat_count; ix++) {
tmp = 0;
err = sscanf (pats[ix], "%5i", &tmp);
if (err != 1 || tmp > 0xff) {//tmp的值不能超过255，因为patterns]为字符型数组
fprintf (stderr, "pattern or value error in pattern # %d [%s]/n",
ix, pats[ix]);
usage ();
}
patterns [ix] = tmp;
}
pat_len = pat_count;
}
//匹配模式，并记下第一次匹配的位置
void search_pattern (void)
{
for (bix = 0; bix < filesize; bix++) {
if (madr[bix] == patterns[0]) {
if (memcmp (&madr[bix], patterns, pat_len) == 0) {
if (num_matches == 0)
firstloc = bix;
num_matches++;
}
}
}
}
#ifdef NOTDEF
size_t get_filesize (int fd)
{
off_t end_off = lseek (fd, 0, SEEK_END);
lseek (fd, 0, SEEK_SET);
return (size_t) end_off;
}
#endif
size_t get_filesize (int fd)
{
int err;
struct stat stat;
err = fstat (fd, &stat);
fprintf (stderr, "filesize: %ld/n", err < 0 ? (long)err : stat.st_size);
if (err < 0)
return err;
return (size_t) stat.st_size;
}
int main (int argc, char *argv [])
{
progname = argv[0];
if (argc < 3)
usage ();
get_pattern (argc - 2, argv + 2);
inputname = argv[1];
inputfd = open (inputname, O_RDONLY);
if (inputfd == -1) {
fprintf (stderr, "%s: cannot open '%s'/n",
progname, inputname);
exit (3);
}
filesize = get_filesize (inputfd);
madr = mmap (0, filesize, PROT_READ, MAP_PRIVATE, inputfd, 0);
if (madr == MAP_FAILED) {
fprintf (stderr, "mmap error = %d/n", errno);
close (inputfd);
exit (4);
}
search_pattern ();
if (munmap (madr, filesize))
fprintf (stderr, "munmap error = %d/n", errno);
if (close (inputfd))
fprintf (stderr, "%s: error %d closing '%s'/n",
progname, errno, inputname);
fprintf (stderr, "number of pattern matches = %d/n", num_matches);
if (num_matches == 0)
firstloc = ~0;
printf ("%ld/n", firstloc);
fprintf (stderr, "%ld/n", firstloc);
exit (num_matches ? 0 : 2);
}
/* end binoffset.c */